The present invention relates generally to inhibitors of arginase and their use for the treatment of pathological states. Two isoforms of arginase have been identified to date. Arginase I (ARG I), which is expressed in the cytosole, and Arginase II (ARG II), which is expressed in mitochondria. The arginase enzymes together with the NOS enzymes play an important role in regulating the levels of free arginine in cells.
The arginases are implicated to play a role in various pathological states. These include, for example, erectile dysfunction, pulmonary hypertension, hypertension, atherosclerosis, renal disease, asthma, T-cell dysfunction, ischemia reperfusion injury, neurodegenerative diseases, wound healing, and fibrotic diseases. Although, the mechanism of action of arginase enzymes in these disease states is still a subject of ongoing research, several studies implicate that the arginase enzymes are often upregulated during pathological disease states.
For example, it is postulated that upregulation of arginase activity results in reduced levels of arginine, which in turn reduces the level of NO a physiologically important signaling molecule that is required for cell division, stimulating enhanced blood flow and for controlling muscular and neurological signal transduction.
In addition to its role in regulating NO levels, arginase also effects production of critical polyamines such as putrescine, spermidine and spermine. As arginase consumes arginine it produces ornithine. Ornithine is subsequently converted to putrescine, spermidine and spermine via ornithine decarboxylase, spermidine synthase and spermine synthase respectively. Thus, the arginase enzymes control physiological signaling events by controlling the intracellular levels of polyamine signal transducers. See Wang, J-Y; and Casero, Jr., R. A., Ed; Humana Press, Totowa, N.J., 2006.
These results implicate, therefore, a role for inhibitors of arginase as candidate therapeutics for the treatment of various disease states. The present invention provides compounds as inhibitors of arginase activity, as well as methods for using the inventive compounds in treatment.